Guidance

MergersMergers: guidance on jurisdiction and procedure

GuidanceHow on how the Competition and Markets Authority (CMA) operates the mergers control regime under the Enterprise Act 2002.

From:
Competition and Markets Authority
Published
10 January 2014
Last updated
2819 OctoberDecember 2025 — See all updates

Documents

Mergers: Guidanceguidance on the CMA’s jurisdiction and procedure (October(December 2025 –version) revised guidance)

PDF, 1.64 MB, 193 pages

Mergers: Guidance on the CMA’s jurisdiction and procedure (January 2025 – revised guidance)

Ref: CMA2

PDF, 1.531.82 MB, 180199 pages

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Mergers: Guidanceguidance on the CMA’s jurisdiction and procedure (2024(October –2025 revised guidance)version)

Ref: CMA2

PDF, 1.321.64 MB, 162193 pages

Mergers: Guidanceguidance on the CMA’s jurisdiction and procedure (2022(January –2025 revised guidance)version)

PDF, 1.051.53 MB, 140180 pages

Details

This guidance providessets adviceout and general information to companies and their advisers on the procedures used by the CompetitionCMA and Markets Authority (CMA) in operating the mergers control regime set out in the Enterprise Act 2002, as amended. It also includessets guidanceout on when thewe CMA will have jurisdiction to review mergers under the Act.

The Octoberguidance is for merging parties and their advisers. We also have a simple guide to how mergers are investigated by the CMA.

Changes to the guidance

December 2025

In revisedDecember 2025, the CMA updated this guidance reflects– updatesand our guidance on merger remedies (CMA87) to reflect procedural changes to merger remedies. We launched a review of our approach to remedies in March 2025, then consulted on changes to our guidance on merger remedies (CMA87).

The changes were designed to embed the CMA’s ‘4Ps’ framework – pace, predictability, process and proportionality – intoin our approach to merger remedies and processes.

The revised guidance took effect on 19 December 2025, and applies to merger cases where the formal phase 1 investigation commences on or after 19 December 2025.

October 2025

In October 2025, the CMA updated this guidance to embed its ‘4Ps’ framework into its mergers process. For more information, go to the the consultation page.

WeAs havepart of the October 2025 review, we also updated the the Merger Notice template and  and guidance on the CMA’s mergers intelligence function (CMA56) to to reflect thesethose changes.

The October 2025 revised guidance took effect on 28 October 2025 and appliesapplied to mergers:

  • where the formal phase 1 investigation commencescommenced on or after 28 October 2025
  • referred to phase 2 on or after 28 October 2025

The CMA hashad started applying the procedural changes described in the revised October 2025 guidance to cases in which the initial draft Merger Notice was submitted after 20 June 2025.

To request previous versions of the guidance, email: general.enquiries@cma.gov.uk

Updates to this page

Published 10 January 2014
Last updated 2819 OctoberDecember 2025 + show all updates

  1. Guidance updated to reflect procedural changes to merger remedies.

  2. Guidance updated to embed the CMA's '4P's framework' in its mergers process

  3. Updated revised CMA2 guidance published.

  4. Updated guidance published

  5. Updated CMA2 guidance to reflect changes to the Enterprise Act 2002 brought about by the National Security and Investment Act 2021.

  6. Updated CMA2 guidance published.

  7. Explanatory note added in reference to the Enterprise Act 2002 (Specification of additional section 58 consideration) Order 2020, which adds a further public interest consideration to section 58 of the Enterprise Act 2002.

  8. Added Water mergers explanatory note

  9. First published.

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